Due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake which occurred on March
11, 2011, TEPCO's facilities including our nuclear power stations have been
severely damaged. We deeply apologize for the anxiety and inconvenience
caused.
With regard to the accident at Fukushima Daiichi Nuclear Power Station, on
April 17, we have compiled the roadmap towards restoration from the
accident and then we updated the progress status of roadmap considering the
current situation, on July 19. Accomplishment of the Step1 target
"Radiation dose is in steady decline" has been confirmed. On November 17,
we updated the further progress.
By bringing the reactors and spent fuel pools to a stable cooling condition
and mitigating the release of radioactive materials, we will make every
effort to enable evacuees to return to their homes and for all citizens to
be able to secure a sound life.
Below is the status of TEPCO's major facilities.
* Underlined are updates from the previous press release.
[Nuclear Power Station]
· Fukushima Daiichi Nuclear Power Station: Unit 1 to 3: shut down due to the
earthquake
(Units 4 to 6: outage due to regular inspections)
* As of 5:00 pm on November 26, the indicator of the gas temperature of
Suppression Chamber read 52.7°C, but at 11:00 pm on the day we confirmed
that it read "Overscaled" (digital recorder). Then, as of 5:00 am on
November 27, it read 102.6°C. Though the readings were not stable, as
there were no significant changes or variations in the temperatures of
the same types of 2 thermometers and the pool water in Suppression
Chamber, we have been investigating the causes for this event including
the possibility of malfunction of the measuring instruments. Later, we
inspected the measuring instruments and estimated that the readings were
overscaled due to certain impacts on the signal detection line seeing
that signal from the temperature detector is not stable. We will keep
monitoring readings of this instrument and also monitor the temperature
using instruments close to it.
* The indicator for the inside of the Primary Containment Vessel (Drywell)
of Unit 2 (base line temperature of the air conditioning unit, local
cooling equipment) read 78.2°C as of 5:00 am on November 27 but at 6:50
am on the day it was confirmed that it read approximately 84°C,
increasing in a staircase pattern. On the other hand, it was also
confirmed that the temperature changes of the bottom of the Reactor
Pressure Vessel and the water in the pool of the Suppression Chamber were
smaller than that of the inside of the Primary Containment Vessel
(Drywell) and that there was no significant change in the temperature.
Now we have been decreasing the flow rate of water injection as stated
below and therefore it is expected that the temperature inside the
Primary Containment Vessel will rise, but, as the line temperature of
which rose in a staircase pattern was only one line of the five lines and
the rest of the lines did not show the same changes, we have been
investigating the causes for this event, including the possibility of
malfunction of the measuring instruments. Later we inspected the
instrument but got no data indicating malfunction, and the readings after
the inspection are not different from those before. Therefore, we
estimated that the signal detection line was somehow affected, which
raised the temperature indicated. We will keep monitoring this instrument
and also monitor the temperature using instruments close to it.
· At 7:11 pm on November 24, we adjusted the flow rate of water
injection from Core Spray System from approx. 7.2 m3/h to approx.
5.6m3/h (for feed water system, the flow rate is kept at 2.9 m3/h).
· On November 26 (from 10:18 am to 11:02 am), we adjusted the flow rate
from Core Spray System from approx. 5.5 m3/h to approx. 4.5m3/h (for
feed water system, the flow rate is kept at 3.0 m3/h).
* For the purpose of the cleaning starting on November 28 to avoid the
performance deterioration of pumps by sucking up sands etc. accumulated
at the bottom of the inlet canal pump room, we stopped the pump (D) of
the residual heat removal system thus suspended cooling the reactor, and
also stopped the pump (C) of the cooling water system thus suspended
cooling the spent fuel pool. When each pump was stopped, the temperatures
of the water in the reactor and the spent fuel pool were 25.7°C and
20.4°C respectively. The planned suspension of cooling is between 7:00 am
to 5:00 pm everyday, and the temperature increases of the water in the
reactor and the spent fuel pool due to the suspension will be approx.
17°C and approx. 4°C per day respectively (we plan to do the cleaning
work for approx. 1 week).
· Fukushima Daini Nuclear Power Station:
Units 1 to 4: shutdown due to the earthquake
· Kashiwazaki Kariwa Nuclear Power Station: Units 5, 6: under normal
operation
(Units 1 to 4 and 7: outage due to regular inspections)
[Thermal Power Station]
- Power supply has returned to normal and facilities damaged by the
earthquake are now being handled in a timely manner.
[Hydro Power Station]
- Power supply has returned to normal and facilities damaged by the
earthquake are now being handled in a timely manner.
[Impacts on Transmission Facilities]
- Power supply has returned to normal and facilities damaged by the
earthquake are now being handled in a timely manner.
[Impacts on Power Supply and Demand Balance]
This winter, there will be some minus factors such as the regular
inspection of Unit 5 at Kashiwazaki-Kariwa Nuclear Power Station. On the
other hand, there will be several plus factors such as the recovery of the
common thermal power stations which suffered the earthquake. As a result,
we expect to secure 54.9 GW (at the end of December), 54.6 GW (at the end
of January), 53.7 GW (at the end of February) supply power.
Compared to the maximum demand in the last winter, which is 51.5 GW, we
will have 2.2 - 3.4 GW generation reserve margin.
We expect to maintain stable power supply this winter, however, as there
remains possibilities of unplanned shutdowns at our power stations and
growth in the demand according to the rapid change in the temperature, we
would like to ask your reasonable effort to save electricity.
We will continue to make our efforts to maintain stable operation and
maintenance of the power facilities in order to "prevent in principle" the
planned blackouts and secure power supply.
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Appendix: Past Progress (As of 9:00 am, November 28, 2011) (PDF 176KB)
Appendix: Past Progress (From March 11, 2011 to July 31, 2011) (PDF 225KB)
* Revised past progress